Salmon Sea Lice Management and Fish Welfare

Sea lice infestation causes tissue damage and welfare harm in farmed Atlantic salmon. Integrated management approaches balance efficacy, welfare and environmental impact.

Key Facts

Lepeophtheirus salmonis is the primary sea lice species affecting Atlantic salmon farms
Sea lice cause lesions, secondary infections and osmoregulatory stress in heavily infested fish
Treatment methods include in-feed medicines, bath treatments and non-medicinal thermal and mechanical methods
Resistance to licensed treatments is increasing, driving adoption of non-chemical approaches
Thermolicer and Hydrolicer mechanical systems remove lice without chemical exposure

Welfare Considerations

Sea lice cause welfare harm through physical damage to skin and scales, secondary bacterial infection of wounds and osmoregulatory stress from damage to the gill and head region. Heavy infestations cause appetite suppression, lethargy and impaired immune function. Treatment interventions themselves carry welfare risks — crowding for treatment, handling stress and some chemical bath treatments cause physiological disturbance. Non-chemical methods including warm water thermolicer treatment reduce chemical exposure but require careful temperature and handling management to avoid thermal shock.

What You Can Do

Choose RSPCA Assured or ASC certified salmon with documented lice management protocols
Ask retailers about their requirements for sea lice management in their salmon supply chain
Support research into sustainable lice management including cleaner fish and vaccine development
Advocate for mandatory sea lice reporting and threshold limits in aquaculture licensing
Consider reducing farmed salmon consumption given ongoing welfare challenges in the industry